This invention relates to blow molding and more particularly to a mold or die construction, particularly adapted for blow molding, wherein an integral hinge is formed on either or both of two halves of a hinged blow molded carrying case or panel assembly.
Blow molding is a technique for producing molded articles of plastic materials and is usually carried out by placing a parison (a tube of heated plastic) between two dies. Upon aligning the dies, such as a male and female die, pressurized air is introduced into the parison, with the parison expanding so as to conform to the shape of the mold cavity defined by the two mating dies. The resultant product or article is a hollow wall structure, the walls being joined at the periphery of the article.
Usually the two halves of a blow molded carrying case are joined by a hinge or series of hinges along respective edges, with the case edges opposite the hinges carrying one or more latches to secure closure. Typically, the hinges are often formed by molding them integrally with respective carrying case halves, and then drilling holes or bores through them, with the holes of the several hinge bosses being aligned so as to accept a hinge pin. U.S. Pat. No. 4,615,464 issued Oct. 7, 1986 to James E. Byrns, incorporated by reference, illustrates a carrying case having two blow molded halves coupled by hinges. However, the hinges must be drilled after the molding operation to provide bores for the hinge pins. The requirement for subsequent drilling after formation of the hinge bosses adds expense to the manufacturing process.